Mechanistic and synthetic work is being carried out en route to electronically and strained ring activated polycyclic benzenoid hydrocarbons. Once synthesized, these compounds are fully characterized with respect to their physical and chemical properties. In addition, the Ames test is being applied to establish the potential and/or relative mutagenic activity. Novel routes to several of these materials are being developed, which require some mechanistic investigation. These routes rely on transition metals as reagents and catalysts, and on unimolecular gas phase rearrangements.